A man writes messages for passengers aboard the missing Malaysia Airlines flight MH370, at a shopping mall in Kuala Lumpur, Malaysia. Search teams racing against time to find the flight recorders from the missing Malaysia Airlines jet crisscrossed another patch of the Indian Ocean on Saturday, four weeks to the day after the airliner vanished. (AP)

SummaryTeams has entered the most intensive phase in the search operations of Malaysia Airlines MH370.

A Chinese patrol ship searching the crashed Malaysia Airlines MH370 today picked up a pulse signal from its black box detector in the southern Indian Ocean, China's

official media reported, in a possible breakthrough in the nearly month-long multinational hunt for the jet.

Haixun 01, searching for the Malaysia Airlines Flight MH370, detected a pulse signal with a frequency of 37.5kHz per second in southern Indian Ocean waters today, state-run Xinhua news agency reported.

The batteries of the black box flight recorders have a life of about 30 days, meaning they will shut down in the next three days.

Officials said the multinational team has entered the most intensive phase in the search operations.

Up to 10 military planes, three civil jets and 11 ships were searching about 217,000 sq km, 1,700 km north west of Perth, to locate the plane's data recorder that could help investigators unravel the mystery of what happened on March 8, the day the Beijing-bound jet suddenly disappeared from radar screens.

China's Liberation Daily reported that three people on board had heard the signals, which were not recorded as they came suddenly.

The frequency of 37.5 kHz per second is currently the international standard for the underwater locator beacon on a plane's black box.

Also, a Chinese air force plane searching for the jet spotted a number of white floating objects in the search area today.

The plane photographed the objects over a period of 20 minutes after spotting them at 11:05 local time.

An Australian pilot on board the plane reported the information to the Joint Agency Coordination Center (JACC), which is coordinating the massive multinational search in the southern Indian Ocean.

The plane was the first to leave Perth International Airport for the day's search schedule today. It arrived at the designated area, about 2,700 kilometres from Perth, this morning.

JACC said in a statement that the weather forecast for today's search is fair, with